Semiconductor light-emitting devices including light emitting diodes (LEDs), resonant cavity light emitting diodes (RCLEDs), vertical cavity laser diodes (VCSELs), and edge emitting lasers are among the most efficient light sources currently available. Materials systems currently of interest in the manufacture of high-brightness light emitting devices capable of operation across the visible spectrum include Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of gallium, aluminum, indium, and nitrogen, also referred to as III-nitride materials. Typically, III-nitride light emitting devices are fabricated by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a sapphire, silicon carbide, III-nitride, or other suitable substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or other epitaxial techniques. The stack often includes one or more n-type layers doped with, for example, Si, formed over the substrate, one or more light emitting layers in an active region formed over the n-type layer or layers, and one or more p-type layers doped with, for example, Mg, formed over the active region. Electrical contacts are formed on the n- and p-type regions.
FIG. 1 illustrates a structure described in more detail in U.S. 2011/0057205. An LED 282 and a transient voltage suppression (TVS) chip 284 are attached to a submount 280. (Metal traces on the submount 280, which connect TVS chip 284 between the power leads of the LED 282, are not shown). Upon a voltage surge, such as due to electrostatic discharge (ESD), the circuit in the TVS chip 284 shorts the transient voltage to ground to bypass the LED 282. Otherwise, the LED 282 may be damaged. TVS circuits are well known. The submount 280 shown in FIG. 1 is part of a wafer on which is mounted many pairings of LEDs and TVS dies. The submount wafer will be later sawed to singulate the LED/TVS pairs. A mold has indentations that are filled with liquid silicone containing phosphor grains. The submount wafer and mold are brought together so that each LED/TVS pair is within the silicone in a single indentation, and the silicone is then cured. The submount wafer is then separated from the mold, and the structure of FIG. 1 results. The molded phosphor lens 286 encapsulates both chips. The type(s) of phosphor used, the density of the phosphor(s), and the shape of the lens 286 are determined by the desired color temperature characteristics. In one embodiment, the phosphor in the lens 286 is a mixture of YAG and red phosphor to create a warm white light when energized by the blue LED 282.